Forming surface relief patterns in poly(olefin sulfone) polymers by electron beam resist methods are well known and are utilized for a variety of applications. For example, poly(1-methyl-1-cyclopentene sulfone) has been used for audio/video recording applications and is more fully described in U.S. Pat. No. 3,935,331 and 3,935,332 by Poliniak et al.; poly(1-butene sulfone) has been employed for integrated circuit mask formation; and poly(cyclopentene sulfone) and poly(bicycloheptene sulfone) for multilayer integrated circuit mask formation.
Surface relief patterns in the poly(olefin sulfone) layers are formed by dissolving a poly(olefin sulfone) in a solvent, forming a wet layer of the poly(olefin sulfone) solution on a substrate such as metal, baking or vacuum drying the wet layer to remove the solvent, exposing the dry layer to a modulated beam of electrons, and developing the poly(olefin sulfone) layer with a solvent to yield the surface relief pattern. In general the surface relief patterns that are formed in the poly(olefin sulfone) have not been found transferable to a metal substrate by use of sputter etching or ion milling operations wherein material is eroded from the relief pattern surface by ion bombardment. This is a disadvantage in many applications such as audio/video recording where a surface relief pattern which is recorded on a polymeric material must be subsequently transferred onto a metal surface so that the metal surface may be employed as a master for stamping the surface relief pattern in large quantities of vinyl discs. In the past poly(olefin sulfones) that could undergo a sputter etching cycle were limited to the poly(olefin sulfones) that undergo a weight loss at a temperature above about 300.degree. C. as determined by thermogravimetric analysis, hereinafter referred to as TGA temperatures. High TGA temperatures were necessary to survive the high temperatures attained during sputter etching. Other more sensitive poly(olefin sulfones) that had low TGA temperatures and could not survive these high temperatures were automatically eliminated from being used in sputter etching operations.
The sputter etching of one particular poly(olefin sulfone), poly(styrene sulfone), has been described by M. J. Bowden and L. G. Thompson, Journal of the Electrochemical Society, 121 1620 (1974). This is a relatively insensitive poly(olefin sulfone), however, and it does not form surface relief patterns with sharp edge definition. Transferring surface relief patterns formed in the more sensitive poly(olefin sulfones) by sputter etching has been desired.